the plants grew outdoors in climates that some of us never experianced in our lives,the rain will cause bud rot,but to say it knocks off resin glands is hard to say and if the rain did knock them off i doubt you would notice it at all...it would take extreme rain and wind to hurt the plant,remember these things grow in rain forest naturally and i doubt those plants are weak and unpotent...and most people who say the rain knocks off resin glands are usually indoor growers who think outdoor growing is worthless or just unexperianced growers...let the plants stay out untill there finished if your going to get a big rain storm one day then sunny the next day leave them out but just make sure you go check the plants the following day give em a shake or to for the extra water and you should be good....never pick early unless its absolutley needed.....just from my experiance never let them stay out after a rain storm and no sun for more than 3 days but then again this always depends on how far along in flowering they are.....

hope this helps